FRITZ!Box 6490 Cable Service - Knowledge Base
Maximum number of calls over FRITZ!Box
If you have configured several Internet telephone numbers in the FRITZ!Box, you can conduct up to four Internet calls over the FRITZ!Box at the same time.
If you cannot conduct more than one call, then your Internet telephony provider does not allow you to conduct several calls at the same time.
Note:The FRITZ!Box allows you to conduct up to three calls at the same time using the DECT base station and up to two calls port at the same time using the "FON S0" port. With IP telephones, you can conduct up to two Internet calls at the same time.